Compressor and granular-material conveying systems



Nov. 28, 1961 w. D. COSKI 3,010,766

COMPRESSOR AND GRANULAR-MATERIAL CONVEYING SYSTEMS Filed April 16, 1959 INVENTOR. WILLIAM D. Cosm BYKMd M ATTORNEYS United States Patent ()filice 3,0 10,7 56 Patented Nov. 28, 1961 3,010,766 COMPRESSOR AND GRANULAR-MATERIAL CONVEYING SYSTEMS William D. Coski, 7900 Rainier Ave., Seattle, Wash. Filed Apr. 16, 1959, Ser. No. 806,981 1 Claim. (Cl. 302-51) The present invention relates to improved compressor and granular-material conveying systems of simple and economical construction aimed at minimum maintenance and ease of operation without damage to the material being handled.

Still additional objects and advantages of the invention will, with the foregoing, appear and be understood in the course of the following description and claim, the invention consisting in the novel construction and in the adaptation and combination of parts hereinafter described and claimed.

In the accompanying drawings:

FIG. 1 is a schematic plan view, partly in section, of my compressor system.

FIG. 2 is a detail fragmentary view of the jet and difiuser arrangement.

FIG. 3 is a schematic elevational view, partly in section of my material conveying system; and

FIG. 4 is a vertical sectional detail view taken as indicated by the line 44 of FIG. 3.

Before referring to the drawings it should be understood that the output pressure of a pressure booster of the centrifugal compressor type is proportional to the pressure and density of the gas at the inlet, and that the flow quantity is a function of the pressure drop across the booster. It follows from these characteristics that if the inlet pressure of a centrifugal pressure booster were continually increased, the output pressure of the booster would also continue to increase. Furthermore, a further pressure differential across the booster would be realized because the gas density would increase responsive to the increasing inlet pressure.

Directing attention to FIG. 1, in the compressor system of the present invention the output of a centrifugal pressure booster is continuously fed back to its inlet to efiect a build-up of the output pressure. This arrangement necessitates the admission of additional gas to make up for the volume loss resulting from the increase in gas density as the pressure rises. This admission is accomplished by the insertion of a jet 11 and diffuser 12 in a recirculating piping circuit 13-14 interconnecting the outlet and inlet of the booster.

As illustrated in FIG. 2, the jet 11 is alined with the difiuser 12 to discharge into the flared mouth thereof. There is a gap between the jet and diffuser so that the surrounding atmosphere will be inducted into the jet stream traversing the gap. Such induction compensates for the the afore-mentioned volume loss and provides the makeup for gas drawn off for useful Work through a discharge line 15 as controlled by a valve 16. This line 15 is shown located in the outlet part 13 of the circuit because of the higher pressure therein, but could also be located in the return section 14.

Summarizing the operation of my compressor system, it is seen that the pressure of the gas from the booster 10 is converted by the jet 11 into velocity and that the resulting high speed jet stream, by discharging into the diffuser 12, has its velocity reconverted into pressure. Simultaneously, pressurized gas can be continuously drawn off from the circuit for useful work while a corresponding amount of gas is inducted into the circuit by the jet stream.

The booster 10, although preferably a centrifugal type, could be a positive displacement compressor having variable speed controls to compensate for changing volume requirements of the system as the operating pressure varies.

In FIG. 3 I have illustrated my compressor system incorporated into my material conveying system, the pressure booster, jet and diffuser being denoted 20-22, respectively. It will be noted that the material 19 to be conveyed, normally granular, is stored in a hopper 23 which is positioned to discharge into the top of the jet stream. The bottom of the latter is preferably closed at 24, but a gap 25 is maintained in the stream for gas make-up as before. This gap is shown for purposes of example as being located between the hopper 23 and the diffuser 22.

A separator 27 of the dynamic type, as for instance a cyclone separator, is placed in the circuit, its inlet being connected by line 29 to the diffuser and its outlet at the top being connected by a return line 30 to the inlet of the pressure booster. The bottom material collecting portion of the separator has a discharge pipe 31 feeding upwardly out of the separator, and leading to a depository 32. This pipe 31 is purposely smaller than the circuit lines 2830.

In the operation of the material handling system, the material 19 falls from the hopper 23 into the jet stream and is carried thereby into the difiuser and along through line 29 into the separator 27. In the latter the material 19 gathers at the bottom under pressure while most of the gas discharges at the top through the return line 30 for recirculating. At the same time, a relatively minor portion of the gas travels downwardly into the mouth of the material discharge line 31 and carries the separated material out of the separator through such line to the depository. While so discharging, the material is in a dense phase in which only a small percentage of gas is entrained. As before mentioned, makeup for the gas is performed by the induction at the gap 25.

A centrifugal compressor will handle gas quantities ranging from about 50% to maximum capacity without loss in efliciency or pressure output, and hence the booster can be efliciently operated at constant speed. Since the rotor of the booster is the only moving part in the system and does not directly convey the material being handled, very little system maintenance is required.

The advantages of the invention, it is thought, will have been clearly understood from the foregoing detailed description of the illustrated preferred embodiment. Minor changes will suggest themselves and may be resorted to Without departing from the spirit of the invention, wherefore it is my intention that no limitations be implied and that the hereto annexed claim be given a scope fully commensurate with the broadest interpretation to which the employed language admits.

What I claim is:

In a material conveying system, centrifugal gas comv pressor means, a venturi having its throat of oblong crossa section defined by opposed pairs of wide and narrow Walls, a supply of air and granular material to be conveyed opening into said venturi through substantially the full expanse of one of said wide walls, separating means, a closed piping circuit including said compressor means, venturi and separating means, said separating means being adapted to separate said granular material from said circuit, and a takeoff from said separating means for conveying said separated granular material to a remote delivery point of reduced pressure in a considerably higher material-to-air ratio than that in said circuit between said venturi and separating means.

References Cited in the file of this patent UNITED STATES PATENTS Vogel-Jorgensen Nov. 29, 1932 Fickey Feb. 21, 1933 Fuller Dec. 1, 1942 Webb Jan. 23, 1951 Lung Apr. 6, 1954 Iisha May 4, 1954 Murray Nov. 26, 1957 

